The present invention relates to a tubing hanger for a flow completion system that is used to produce oil or gas from a well. More particularly, the invention relates to a tubing hanger which comprises an annulus bore extending generally vertically therethrough and a remotely-operable closure member for controlling fluid flow through the annulus bore.
In a conventional flow completion system, a tubing hanger is landed in a wellhead housing which is installed at the upper end of a well bore, and a Christmas tree is connected to the top of the wellhead housing over the tubing hanger. The tubing hanger supports at least one tubing string which extends into the well bore and defines both a production bore within the tubing string and a production annulus surrounding the tubing string. In addition, the tubing hanger comprises at least one vertical production bore for communicating fluid between the tubing string and a corresponding production bore in the Christmas tree, and typically at least one vertical annulus bore for communicating fluid between the tubing annulus and a corresponding annulus bore in the christmas tree. Furthermore, the tubing hanger may comprise one or more vertical service and control conduits for communicating control fluids and well chemicals through the tubing hanger to devices or positions located in or below the tubing hanger.
During installation and workover of the conventional flow completion system, the tubing hanger annulus bore must typically remain closed until either the christmas tree or a blowout preventer (xe2x80x9cBOPxe2x80x9d) is connected to the wellhead housing. However, after the christmas tree or BOP is installed on the wellhead housing, the tubing hanger annulus bore must usually be opened to allow for venting of the tubing annulus during production or circulation through the tubing annulus during workover. In prior art tubing hangers for conventional flow completion systems, a wireline plug is typically used to close the tubing hanger annulus bore. However, each installation or removal of the plug requires a special trip from a surface vessel. Moreover, although several versions of hydraulically actuated valves for controlling flow through the tubing hanger annulus bore have been patented, these valves have for the most part been impractical to implement.
In accordance with the present invention, these and other disadvantages in the prior art are overcome by providing a tubing hanger for a flow completion system which comprises a christmas tree that is connected above a wellhead housing that includes a central bore in which the tubing hanger is supported. The tubing hanger comprises a generally annular body, a first annular seal which is positioned between the body and the central bore, a production bore which extends generally axially through the body, and an annulus bore which extends generally axially through the body from below the tubing hanger to a portion of the central bore that is located above the first seal. In addition, the annulus bore comprises a generally lateral first branch which is connected to a generally axial second branch, and the tubing hanger includes a remotely-actuated closure member which comprises a gate that is moveable generally axially across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch.
In accordance with a further aspect of the present invention, the tubing hanger also comprises a second annular seal which is positioned between the body and the central bore above the first seal, and a gate cavity in which the gate is at least partially positioned and which extends into the body from between the first and second seals. Furthermore, the tubing hanger includes an actuating mechanism for the gate which is positioned in a conduit that preferably extends generally axially through the body above the gate cavity.
Thus, the tubing hanger of the present invention permits flow through the annulus bore to be reliably controlled from a remote location without the use of wireline plugs. In addition, the pressure within the gate cavity is contained by the first and second seals without the need for separate sealing means for this purpose. Furthermore, since the gate and its actuating mechanism are oriented generally axially within the tubing hanger, the closure member occupies a minimum radial cross-sectional area of the tubing hanger.
These and other objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments.